The development of the grape berry cuticle in relation to susceptibility to bunch rot disease

Some physical and morphological factors of grape berry cuticlewere investigated at different developmental stages of threeclones ofVitis vinifera cv. Pinot noir. The surface morphologyof grape berries was examined by scanning electron microscopyand cuticle anatomy was examined by light and transmission electronmicroscopy. During the period from flowering to maturity, thecomposition of the cuticular waxes changed, corresponding withan increase of waxy deposits and significant modifications ofthe wax surface morphology. The content in cutin per unit surfacedecreased more than 2.5-fold between berry set (16 d after anthesis)and veraison of the grape berries, and might predispose thegrape berry to fungal infection. This result was correlatedwith the differentiation of the cuticle layers and particularlywith a decrease in the thickness of the primary cuticle at harvest. Key words: Botrytis cinerea, cuticle, cutin, epicuticular waxes, Vitis vinifera L